> > > You need to wrap this with a read_lock(&tasklist_lock) to be safe, I
> > > think.
> >
>
> It will depend on the data accuracy. If the information on cpu usage is
> very accurate then it becomes a way to analyse what is happening to
> tasks you don't own - such as say cryptographic functions in the web
> server...
>
> Otherwise, or with an owner check I see no real problem with the concept
So, is the following patch right ? I've added both the lock and the owner
check...
Do you think it may be an interesting feature to be inserted in the kernel ?
Many thanks,
Claudio
diff --git a/kernel/sys.c b/kernel/sys.c
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1746,9 +1746,25 @@ int getrusage(struct task_struct *p, int
asmlinkage long sys_getrusage(int who, struct rusage __user *ru)
{
- if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
- return -EINVAL;
- return getrusage(current, who, ru);
+ if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) {
+ struct task_struct* tsk;
+ struct rusage r;
+ read_lock(&tasklist_lock);
+ tsk = find_task_by_pid(who);
+ if (tsk == NULL) {
+ read_unlock(&tasklist_lock);
+ return -EINVAL;
+ }
+ if ((current->euid != tsk->euid) &&
+ (current->euid != tsk->uid)) {
+ read_unlock(&tasklist_lock);
+ return -EINVAL;
+ }
+ k_getrusage(tsk, RUSAGE_SELF, &r);
+ read_unlock(&tasklist_lock);
+ return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
+ } else
+ return getrusage(current, who, ru);
}
asmlinkage long sys_umask(int mask)
--
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